Ukraine's association with the European Union does not contradict their observer status in the Customs Union and the Eurasian Economic Union, Russian presidential aide Yury Ushakov said.

"No, there is no contradiction," Ushakov told a briefing on Monday, responding to a question from Interfax as to whether Ukraine can simultaneously be an observer in the Eurasian Economic Union and the Customs Union and an associated member of the EU in the future.

Ushakov said Ukraine is already an observer and its representatives have taken part in several sessions of the Eurasian Troika.